Transcript Biogeochemical Cycles Power Point

CHAPTER
3
Earth’s Environmental Systems
The Gulf of Mexico’s
Dead Zone
• Nutrient-rich runoff causes plankton blooms and
hypoxia—low oxygen levels—in the Gulf of Mexico.
• Hypoxia kills or displaces marine organisms, causing a
decline in the fisheries and the fishing industry.
• U.S. government and farmers debate the need to cut
down on fertilizer use.
Talk About It Do you think the distance between the source of
the nitrogen and phosphorus and the dead zones themselves
makes it difficult to manage this problem? Why or why not?
Lesson 3.1 Matter and the Environment
Water’s abundance is a primary reason there is life
on Earth.
Lesson 3.1 Matter and the Environment
Atoms and Elements
• Atoms are the basic unit
of matter.
• Nucleus: Contains
protons and neutrons
• Electrons: Move around
the nucleus
• An element is a
substance that cannot
be broken down into
other substances.
Did You Know? There are 92 elements
that occur naturally, and scientists have
created about 20 others in labs.
Lesson 3.1 Matter and the Environment
Bonding
• Atoms combine by bonding:
• Covalent bonds: Electrons
are shared.
• Ionic bonds: Electrons are
transferred.
• Molecule: Two or more atoms
joined by covalent bonds
• Compound: Substance
composed of atoms of two or
more different elements
Covalent bonding
Ionic bonding
Lesson 3.1 Matter and the Environment
Organic and Inorganic Compounds
• Organic compounds:
Consist of covalently bonded
carbon atoms and often
include other elements,
especially hydrogen
• Hydrocarbons: Organic
compounds, such as
petroleum, that contain only
hydrogen and carbon
• Inorganic compounds: Lack
carbon-to-carbon bonds
Organic compounds include natural gas,
petroleum, coal, and gasoline.
Lesson 3.1 Matter and the Environment
Solutions
• A mixture is a combination of elements, molecules, or
compounds that are not bonded chemically.
• Solutions are mixtures in which all ingredients are equally
distributed.
• Mixtures can be solids, liquids, or gases.
Blood, sea water, plant sap, and metal
alloys, such as brass, are all solutions.
Lesson 3.1 Matter and the Environment
Macromolecules
• Large organic compounds that are essential to life
• Proteins: Serve many functions; include enzymes
• Nucleic Acids: Direct protein production; include
DNA and RNA
• Carbohydrates: Provide energy and structure;
include sugars, starch, and cellulose
• Lipids: Not soluble in water; many functions;
include fats, waxes, and hormones
Lesson 3.1 Matter and the Environment
Water
• Water is required by all living
things for survival.
• Hydrogen bonding gives
water many unique
properties:
• Cohesion
• Resistance to temperature
change
• Less dense when frozen
• Ability to dissolve many
other molecules
Lesson 3.1 Matter and the Environment
Acids, Bases, and pH
• The separation of water
molecules into ions causes
solutions to be acidic, basic,
or neutral.
• The pH scale measures how
acidic or basic a solution is.
• pH of 7—Neutral: Equal
concentrations of H+ and OH-
• pH below 7—Acidic: Relatively
high concentration of H+
• pH above 7—Basic: Relatively
high concentration of OH-
Lesson 3.2 Systems in Environmental Science
Positive feedback loops can help
erosion turn a fertile field to desert in
just a few years.
Dust storm, Stratford
Texas, 1930s
Lesson 3.2 Systems in Environmental Science
Interacting Systems
• Inputs into Earth’s interconnected systems include energy,
information, and matter.
• Feedback loops regulate systems.
Negative feedback loop
• Negative feedback
loops: Result in
stabilization
of a system
• Positive feedback
loops: Result in a
system moving
to an extreme
Did You Know? Predator-prey cycles are negative feedback loops.
If prey populations rise, predator populations can rise in response,
causing prey populations to fall. Then predator populations may
decline, allowing prey populations to rise again, and so on.
Lesson 3.2 Systems in Environmental Science
Spheres of Function
• Earth can be divided into spheres that are defined
according to their location and function.
Lesson 3.3 Earth’s Spheres
The Geosphere
• Rocks and minerals on and below Earth’s surface:
• Crust: Thin, cool, rocky outer
“skin”
• Mantle: Very hot and mostly solid
• Core: Outer core is molten metal,
inner core is solid metal
Rock formation, Ouray National Wildlife Refuge, Utah
Lesson 3.3 Earth’s Spheres
The Biosphere and Atmosphere
• Biosphere: The part of Earth in which living and
nonliving things interact
• Atmosphere: Contains the gases that organisms
need, such as oxygen; keeps Earth warm enough
to support life
Earth’s atmosphere, seen from space
Lesson 3.3 Earth’s Spheres
The Hydrosphere
• Consists of Earth’s water
Greenlaw Brook, Limestone, Maine
• Most of Earth’s water
(97.5%) is salt water.
• Only 0.5% of Earth’s
water is unfrozen fresh
water usable for drinking
or irrigation.
• Earth’s available fresh
water includes surface
water and ground water.
Did You Know? If it is depleted, groundwater
can take hundreds or even thousands of years
to recharge completely.
Lesson 3.3 Earth’s Spheres
The Water Cycle
Lesson 3.4 Biogeochemical Cycles
A carbon atom in your body today may have
been part of a blade of grass last year, or a
dinosaur bone millions of years ago.
Fossilized bones in a
Colorado dig.
• What is a nutrient?
• What molecular nutrients are needed by all living
things?
Biogeochemical Cycles
• In a self sustaining ecosystem - Nutrients cycle
endlessly between living and nonliving realms of the
environment
4 Components of a self sustaining
ecosystem
• Abiotic Factors
sun, wind, water, minerals,light
• Biotic Factors
living things, their products /wastes
• Energy flow
begins with sun as primary source
• Nutrient cycles
Lesson 3.4 Biogeochemical Cycles
What is matter?
• Matter is made of atoms and
has mass.
• Matter may be transformed, but
cannot be created or destroyed.
•.
Lesson 3.4 Biogeochemical Cycles
What are nutrients?
• Matter that is required to support
life.
• Macronutrients – required in
large amounts. C, N, P, Ca
• Micronutrients – molybdenum,
magnesium
Did You Know? Organisms require
several dozen nutrients, such as nitrogen,
phosphorus, and carbon, to survive.
• Small deficiencies in either is
very harmful
•.
Nutrient cycle (or ecological recycling) is the
movement and exchange of organic and inorganic
matter between the biosphere, atmosphere,
hydrosphere and lithosphere back into the
production of living matter.
Nutrient Cycle = Biogeochemical Cycle
• BIO – Life
•
GEO – EARTH
•
CHEMICAL – MOLECULES
These cycles rely on interactions
between abiotic and biotic
factors
Carbon Cycle
• Basis of all the Organic molecules found in living
things.
• These include:
• Proteins
• Carbohydrates
• Lipids
• Nucleic Acids
Lesson 3.4 Biogeochemical Cycles
The Carbon Cycle
Human Impacts on Carbon Cycle
• Burning of fossil fuels has released large amounts of
stored carbon from the lithosphere into atmosphere
• Burning of rainforests to clear land for
ranching/farming/other development also has
increased the release of stored carbon to atmosphere
Phosphorus Cycle
• Basis for phospholipid molecules needed to form cell
membranes
• Needed to form the important biological molecules of
ATP (E source), DNA, RNA, Proteins
Human Impacts on Phosphorus Cycle
• Important component of fertilizer – must be mined
• Added to detergents to increase sudsing and released
in wastewater
• It is bound up in rock and thus often not easily
dissolved by roots of plants making it a limiting factor
to plant and algae growth. When added to a water
body it can lead to eutrophication.
• As these producers die, bacteria and fungi act as
decomposers a process which requires them to use
dissolved oxygen. This reduces the amount of
available oxygen to other organisms, a condition
known as hypoxia
• Large areas of hypoxia are known as dead zones.
• Ex. Gulf of Mexico Dead Zone
Lesson 3.4 Biogeochemical Cycles
The Phosphorus Cycle
Lesson 3.4 Biogeochemical Cycles
The Nitrogen Cycle
The nitrogen cycle is of particular interest
to ecologists because nitrogen availability
can affect the rate of key ecosystem
processes, including primary
production and decomposition.
Nitrogen Cycle
•Process by which nitrogen is
converted between its various
chemical forms. This
transformation is carried out
through both biological and
physical processes.
Important transformations in
Nitrogen cycle
.
• Nitrogen Fixation,
•Ammonification,
•Nitrification,
•Denitrification.
Nitrogen Fixation –
Conversion of nitrogen
gas into usable
ammonia and nitrates
by physical (lightning)
or biological
(Rhizobium bacteria)
processes
Legumes- family of plants
such as beans and clover
that form a relationship with
Rhizobium bacterial
species.
Bacteria form colonies in
plant roots and the plant
responds to the Infection by
swelling . The swollen
areas are called root
nodules.
This symbiotic
relationship is mutualism
as both species benefit.
Bacteria obtain a safe place
to live and a “free” meal as
they absorbs nutrients
stored in plant roots.
Plant obtain fixed nitrogen
through the action of the
Ammonification –
Nitrogen in organic
waste products
/detritus is converted
to Ammonia(NH3) by
decomposers (specific
bacteria and fungal
species)
(Think cat urine…)
Ammonia buildup in
soil is toxic to plants
Nitrification –
Conversion of Ammonia(NH3)
to Nitrates – a 2 step process.
Step 1:
Ammonia to Nitrites NO2- by
Nitrosomonas
Step 2:
Nitrites to Nitrates NO3- by
Nitrobacter bacteria
Denitrification –
Conversion of Nitrates
NO3-to N2 gas which is
released to
atmosphere.
Carried out by
denitrifying bacterial
species Pseudomonas
and Clostridium